Conventionally, laminated glass obtained by inserting an interlayer film of a polyvinyl butyral resin between at least two glass plates is excellent in transparency, weather resistance, adhesion strength, and penetration resistance and further provided with a capability of preventing scattering of glass debris as basic properties, and accordingly has been used widely for window glass of automobiles and buildings.
To heighten the beauty of laminated glass, laminated glass using a color interlayer film comprised of a polyvinyl acetal resin containing a coloring agent has also been used widely.
However, there is a fear that the color interlayer film may turn its color to white if the film is put in highly humid atmosphere, resulting in discoloration of its original color into white. Further, the color interlayer film is desired to have high transparency and there arises a problem that if the color interlayer film has a light ray transmittance exceeding 50%, even slight whitening discoloration tends to be noticeable. Therefore, it has been desired to develop a color interlayer film for laminated glass capable of preventing whitening of the color interlayer film and maintaining the original color of the color interlayer film, and laminated glass using the interlayer film.